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BI110 Study Guide - Midterm Guide: Passive Transport, Symporter, Pinocytosis

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Matthew Smith
Study Guide

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Biology Midterm #2
18. Membrane Transport
1. What is passive transport?
Movement of a substance across a membrane without the need to expend chemical
energy (ATP)
2. What can passive transport be driven by?
3. What is diffusion & what does the rate depend on?
Net movement of a substance from high concentration to low concentration
Depends on the concentration gradient
oMore difference = substance moves faster
4. What is a concentration gradient?
Concentration difference on 2 sides of the membrane
5. What effect does temperature have on diffusion rate?
Higher the temperature = greater the diffusion rate
6. What 3 things determine the rate of diffusion?
Concentration gradient
7. What does equilibrium mean?
Movement is the same in both directions
8. What is simple diffusion?
Passive transport of substances across the lipid portion of the membranes with their
concentration gradients
9. What molecules move the fastest & what molecules move the slowest?
Small, uncharged molecules move FAST

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Large, charged molecules move SLOW
10. What is osmosis?
2 compartments are separated by a membrane permeable to water but not the solute
Water molecules move across the membrane to equalize concentration of the solute on
both sides
11. What are the 3 types of tonicity?
12. What is an isotonic solution?
Same solute concentration on both sides
No net movement
13. What’s a hypotonic solution?
Cells has a lower solute concentration than the outside
Water moves INTO the cell
14. What’s a hypertonic solution?
Cell has higher solute concentration than the outside
Water moves OUT of the cell
15. What are the 3 types of transport?
16. What’s co-transport?]
When 2 substances are moved at the same time
Symport & Antiport
17. What’s Uniport?
1 substance moved in 1 direction
18. What’s Symport?

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2 substances moved in 1 direction
19. What’s Antiport?
2 substances moves in opposite directions
20. What’s facilitated diffusion?
Passive transport of substances at a higher rate than their lipid solubility
21. What are aquaporins?
Membrane channels that allow water to cross the cell membrane
22. What is a gated channel?
A channel that is triggered (gated) by signal molecules
23. What does a carrier protein do in respect to concentration?
It conforms so that it’s active site is exposed towards the region of higher concentration
24. Describe what sodium/potassium pumps do.
3 sodiums bind to the pump on the cytoplasmic side
ATP hydrolysis phosphorylates the pump
The pump changes shape & releases the sodiums
2 potassiums bind to the pump on the extracellular side
Phosphate group is released, potassiums are allowed through
25. What is the net effect of the sodium/potassium pump?
Increases the concentration of sodium outside the cell and potassium inside the cell
26. What is secondary active transport?
Movement of a substance is indirectly achieved by the movement of a 2nd substance
27. What is osmotic pressure?
Pressure needed to prevent water from passing through to a more concentrated solution
28. What’s water potential?
Tendency of water to move from one area to another
29. What’s osmoregulation?
Process by which living things control their concentration of water & solutes
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